1. Field of the Invention
The invention relates to hand trucks; and, more particularly, to a stair tread engaging device used on a hand truck to provide better mobility of the hand truck.
2. Description of the Prior Art
Hand trucks have been known for many years and are used to tote heavy loads from one location to another. Generally speaking, such hand trucks comprise wheels which rotate along a surface. The wheels alone, however, are not suitable for moving the hand truck up and down stairs or the like. For this reason, stair tread engaging devices have been suggested for facilitating movement of the truck on stairways by allowing free movement of the truck on stairways by allowing free movement of the truck body with respect to the stair treads. One such device is disclosed in U.S. Pat. No. 2,301,341 to Stevens et al and such device cooperates with the truck wheels to enable the user to easily and expeditiously handle a loaded truck in ascending and descending a stairway.
However, devices of the type known in the past rely on a plurality of bearings as roller means which abut against each other while freely moving around the track of the tread engaging device. If one of these bearings sticks, the rest jam up stopping movement of the bearings or rollers in the track. Thus, any twisting or turning of such device might cause all of the roller means to jam. There is thus a need for a stair tread engaging device which has reduced friction in movement and is non-jamming.